In recent years, digital camera, which is capable of simply transmitting images into a personal computer, has become popular accordance with popularization of personal computers. It has also popularized that a digital camera is employed into an information processing apparatus, such as a mobile computer, a cellular phone, and a PDA (Personal Digital Assistance). In accordance with the popularization of digital cameras, a smaller sized digital camera has been required. Thus it is necessary to further minimize the size of the imaging optical system.
The tendency to higher resolution of an image pickup device and to a bigger sized screen for the images has progressed. Japanese Laid-Open Patent Publication Nos. 2003-322792 and 2004-163849 disclosed small sized imaging optical systems which are capable of corresponding to the image pickup device.
The imaging optical systems disclosed in Japanese Laid-Open Patent Publication Nos. 2003-322792 and 2004-163849 are designed to minimize the size of the imaging optical systems by using three lenses. However, it is hard to say that the imaging optical systems have enough optical performances in aberration correction, such as chromatic aberration.